Efficacy of Bio-Rational Insecticides in Controlling Thrips in Summer Country Bean

Aims: To study the efficacy of biorational insecticides in controlling thrips in summer country bean.

Study design: The study used a single component Randomized Complete Block Design (RCBD) with three replications.

Place and Duration of Study: The experiment was conducted in the central farm of Sher-e-Bangla Agricultural University, Dhaka, Bangladesh from March to May 2021.

Methodology: The experiment consisted of seven treatments and was laid in a single factor Randomized Complete Block Design (RCBD) with three replications. The experiment consists of the following management practices: T1=Spraying Neem oil @ 6 ml/L of water at 7 days interval, T2=Spraying Neem leaf extract @ 200 mg/L of water at 7 days interval, T3= Mehgoni leaf extract @ 200 mg/L of water at 7 days interval, T4=Tobacco leaf powder @ 30 mg/L of water at 7 days interval, T5= Spraying Spinosad @ 0.4 ml/L of water at 7 days interval, T6=Spraying Biotrin @1.4 ml/L of water at 7 days interval and T7= Untreated control.

Results: Among the seven (7) treatments the lowest number of thrips (2.50 plant-1) was observed in T5 (Spraying Spinosad @ 0.4 ml/L of water at 7 days interval), while highest number of thrips (16.67 plant-1) was observed in T7 (Untreated control). The highest percentage of thrips reduction over control (85.50%) was observed in T5 (Spraying Spinosad @ 0.4 ml/L of water at 7 days interval) treatment. The present study revealed that the lowest number of thrips as insect pest and increased plant, leaf, inflorescence and pod infestation, different yield contributing characters and yield of country bean might be obtained by using the treatment T5 (Spraying Spinosad @ 0.4 ml/L of water at 7 days interval) besides T6 (Spraying Biotrin @ 1.4 ml/L of water at 7 days interval) performed as second best treatment whereas, T7 (Control) and T3 (Mehgoni leaf extract @ 200 mg/L of water at 7 days interval) may protect the country bean at lowest rate in summer.

Conclusion: It can be concluded that, spraying of Spinosad @ 0.4ml/L of water at 7 days interval as a bio-rational management practice for thrips population control for country bean variety BARI Sheem-4 in summer reduced the infestation of thrips at the most satisfactory level.